Reports suggesting that cannabis has a deleterious effect on intelligence, attention span and memory for youngsters under 18 who use the drug follow the insights of a piece of research by King's College and Duke University using data going back to 1972.

I first smoked cannabis in 1967 when I was 18. I enjoyed the experience – it seemed to heighten my sense of aesthetic appreciation and stimulate my creative juices. And it continued to do so, time after time, year after year. I'm not alone in these perceptions: many artists, musicians, writers and people working in all areas of creative endeavour have experienced the same or a similar reaction. I smoked fairly regularly for 44 years. I quit at the beginning of 2011 because of concerns over the state of my lungs.

All through this period various medical and governmental bodies issued advice about the dangers of taking illegal drugs. However, two of the world's most lethal drugs were legal. This fact totally undermined the warnings concerning drugs like cannabis and the psychotropics, which, though illegal, were demonstrably less dangerous than tobacco and alcohol. As an unfortunate consequence, a whole generation learned to ridicule and ignore all governmental advice on the subject.

I believe that my long-term use of cannabis, while being bad for my lungs, has had no adverse effect on my mind, but two factors have made me consider again the potential problems of cannabis. I was an adult when I began smoking hash and grass and so were the friends I smoked with. Cannabis at this time was little known outside the Jamaican community in the UK and was not a drug taken by children or youngsters. That changed with time.

The other change is the wider availability of high-strength varieties of cannabis, known as skunk. These produce a range of effects which vary from the psychedelic to the catatonic. It is difficult to think, let alone talk, under the influence of many of these powerful substances. Even so, experienced adult users can generally handle and enjoy the mind-bending effects of skunk. It's a different matter with neophytes and youngsters.

I smoked openly in front of my daughter, but never encouraged her to follow my example, thinking that she would be able to make up her own mind when she was an adult. She did, deciding it wasn't for her. At that stage I had no scientific basis for my decision, it just seemed right.

All parents know that teenage brains don't work in the same way as adult brains. If you accept the findings of this study – as I do – it would appear that the best thing you can do for your children is to explain to them why premature use of these psychoactive substances could have a negative effect on their future prospects.